In general you are doing well for somebody who has only done it a few times, but the skiing in your video looks tiring. I’m impressed if you kept that up for 20k.
Try to slow your tempo and go for a longer glide. A rushed tempo is often a result of not being well balanced over the gliding ski, so you feel the need to take quick steps to avoid falling over. Practice with no poles, and stretch out each glide as much as you can.
Think about inserting a glide between each skate and pole motion. For the V2 (aka 1 skate) you are doing here, think skate-glide-pole-glide.
I think you are planting your poles too far back and relying too much on your arms to pole. Reach up higher, plant them about at your toes, and lean down into the poles with your upper body to get a more powerful pole action. Maybe practice double poling in the classic tracks. The first part of the poling action is like an ab crunch with little or no arm movement, then you extend your arms behind you as the crunch finishes.